Electronic devices such as central processing units (CPUs) of computers generate large amounts of heat during their normal operations. The heat must be quickly removed to keep the CPUs working within their normal temperature ranges. Typically, heat dissipation devices such as heat sinks are provided to the CPUs for heat dissipation.
Conventional heat sinks such as aluminum extrusion type heat sinks are widely used for heat dissipation of electronic devices. The extrusion heat sink is integrally formed which generally includes a heat sink base and a plurality of cooling fins extending from the base for increasing the heat dissipating surface area of the heat sink. However, due to limitations of molding and extrusion technology, the height of fins of an extrusion heat sink is limited and the spaces between adjacent fins cannot be made as desirably narrow. The density of the heat sink is therefore limited, which greatly limits the heat dissipating surface area of the heat sink.
To solve the aforesaid drawback of aluminum extrusion type heat sink, another kind of heat sink having a plurality of cooling fins which are manufactured independently and then assembled has been developed. The assembled cooling fins are then soldered to a heat sink base. This kind of combined heat sink provides a higher fin density and a larger heat dissipating surface area. However, the soldering process renders unduly thermal resistance existing between the cooling fins and the base, which decreases the cooling efficiency of the combined heat sink.